When pondering how to add POSIX.4 shared memory areas to linux itoccured to me that probably the easiest way would be just to implementa simple filesystem, and code into libc in which directory to look.

It also occured to me this would be a good opportunity to work onadding dirty page support to the page cache code and I have done thatas well.

The quick synopsis of what I have written is as follows:A complete filesystem that resides in swap, and for kicks and reduced space consumption uses a btree for all of it's directories.A patch to allow sync to sync mmaped files, as well as everything else.A patch to allow the page cache to handle dirty filesA patch to allow the swapoff to work with swap pages that do not reside in page tables. SYSV shared memory probably should be modified to work with this.

This is an alpha release. The filesystem is fully functional. Buthas some races. Extra eyes, and testers welcome.